Carbohydrates and fats are common constituents of processed food products. These ingredients have critical functional significance with regard to the appearance, taste, mouth feel and other organoleptic qualities of food. However, fats/oils and starch-derived carbohydrates utilized extensively in processed foods can be metabolized by the human body and thus contribute significantly to the calorie content of such foods.
In recent years consumers have become increasingly health conscious. Many individuals are attempting to minimize their intake of high-calorie foods and foods containing high levels of fat. Consumers are demanding reduced calorie and low-fat versions of traditional processed foods. Consequently there exists an expanding need for food additives which can be used as functional substitutes for the calorie-imparting contents of processed foods without adversely affecting organoleptic quality.
I have discovered that a cellulase hydrolysate of tamarind endosperm polysaccharide meets that need. The tamarind hydrolysate is unique in that unlike other carbohydrate hydrolysates it comprises 2 predominant (typically) 70%) oligosaccharides - oligosaccharides believed to have degrees of polymerization (DP) of 7 and 9, some DP 8 oligosaccharides with most of the remainder monosaccharides and DP.ltoreq.6 oligosaccharides. The hydrolysate can be processed to remove monosaccharides and DP&lt;6 oligosaccharides. The tamarind hydrolysate can be substituted at high levels for a portion of the metabolizable carbohydrate components of processed foods without compromising the organoleptic qualities of the resulting reduced calorie foods. Significantly, its use also allows reduction of the fat content of those processed foods.
Tamarind polysaccharide is obtained from the seed of the tamarind tree, Tamarindus indica, a common forest and cultivated tree found primarily in India, Burma, Bangladesh and Sri Lanka. Tamarind fruit are in the form of 10-15 cm long pods consisting of about 55% pulp, about 34% seed, and about 11% shell and fiber. Tamarind seed became a commercial source of gum in 1943 when an Indian research institute discovered the gum's utility as a paper size. Since then, tamarind endosperm polysaccharide has found many commercial applications. In 1988 alone, over 800 metric tons of tamarind seed gum were exported from India.
A variety of uses for the isolated tamarind seed polysaccharide have been developed. See Rao and Srivastava, "Tamarind" in Industrial Gums, R. L. Whistler and J. H. Bemiller, eds., 1973, pp. 402-407. The polysaccharide has the ability to form jellies with sugar concentrates over a wide pH range. It has also been used as a stabilizer in ice creams and mayonnaise. Further, the textile industry has employed tamarind polysaccharide for sizing, finishing and printing cotton and artificial silk. In the cosmetics industry, tamarind polysaccharide has been used for preparing emulsions of essential oils, shaving creams and dentifrices. It has also found use as a binder in the manufacture of compressed pills and tablets, as an excipient in making greaseless ointments and as a gelling agent in the preparation of colloidal iodine jelly.
In accordance with the present invention, a cellulase enzyme hydrolysate of tamarind endosperm polysaccharide is utilized as a multi-functional, but non-metabolizable food additive. Further in accordance with this invention tamarind polysaccharide is converted in high yield to a food grade hydrolysate believed to comprise principally, DP 7 and DP 9 oligosaccharides using commercial cellulase. Preferably the polysaccharide hydrolysate product is processed, prior to use in accordance with this invention, to reduce the amount of oligosaccharides in the hydrolysate having a DP less than 6. In a preferred embodiment the hydrolysate is treated to remove at least a portion of the metabolizable monosaccharides produced during enzymatic hydrolysis.
Commercially available cellulases selectively hydrolyre tamarind polysaccharide to produce initially an oligosaccharide mixture comprising DP 7 and DP 9 oligosaccharides. If enzyme action is allowed to continue, the DP 9 oligosaccharide is further hydrolyzed to form a DP 7 oligosaccharide. Typically, enzymatic hydrolysis of tamarind polysaccharide in accordance with this invention is continued until the hydrolysate solution reaches a near constant viscosity (when DP 7 and DP9 oligosaccharides are the principal oligosaccharide hydrolysis products), after which time the hydrolysate solution is heated to terminate hydrolysis and to precipitate soluble proteins which then can be removed by filtration. Preferably the solution is treated to remove at least a portion of the hydrolysate oligosaccharides of DP less than 6, optionally decolorized by carbon treatment, and then freeze dried, spray dried or roll-dried to provide a multi-functional, yet non-metabolizable food additive as a free-flowing powder.
The tamarind hydrolysate can be substituted for up to 60% of the digestible carbohydrates in processed food products without adversely affecting product processing or food product organoleptic properties. Further, it has been found that when the tamarind polysaccharide is used as a carbohydrate substitute, fat content can also be reduced up to 25%. Thus use of the tamarind hydrolysate as a carbohydrate substitute in processed foods enables a significant reduction in calorie content. Significantly, too, because the hydrolysate has a more homogeneous composition (a significant percentage by weight of DP 7-DP 9 oligosaccharides) than other art-recognized carbohydrate hydrolysates, its functional performance is highly predictable in a wide variety of processed food products. Another characteristic of the tamarind polysaccharide enzymatic hydrolysate which derives from its predominant DP 7/DP 9 oligosaccharide content is that, unlike art-recognized food additive gums, the polysaccharide hydrolysate can be used at high levels in processed foods without adversely affecting the processing thereof due to elevated viscosities.